Fastening assembly

ABSTRACT

A fastening assembly includes a panel, a fastener and a primary anode insert. The panel defines an aperture and the fastener includes a shaft portion disposed within the aperture. The primary anode insert may be disposed adjacent to a reaction region of the fastener. Alternatively, the fastening assembly may include a fastener and a primary anode insert. The fastener includes a shaft portion which is configured to be disposed within at least two aligned component apertures. The primary anode insert may be also be disposed adjacent to a reaction region of the fastener.

TECHNICAL FIELD

The present disclosure relates to an improved fastening assembly whichis resistant to galvanic corrosion.

BACKGROUND

Fastener assemblies come in a variety of shapes, sizes, designs andmaterials. Many fastening assemblies include not only a fastener 114such as a bolt, pin or screw, but also will include a fastener insert122 to be positioned within a tapped hole of a substrate or threaded nutbarrel 178 as shown in FIGS. 1A-1B. A bracket may also be viewed as acomponent of a fastening assembling given that a bracket may be used tocouple one member to another member.

Stainless steel fastener have been passivated and coated with zincchromate in an effort to prevent galvanic corrosion. As is generallyknown, galvanic corrosion is an electrochemical process betweendissimilar metals and alloys having different electrode potentials suchthat one metal (the anode) corrodes preferentially when it is inelectrical contact with a dissimilar metal (the cathode) in the presenceof an electrolyte (ex: water and road salt). However, the application ofthe zinc chromate requires strict quantitative controls and isconsidered labor intensive. The installation tools for the fasteners mayrequire frequent cleaning to prevent build-up of the zinc chromate onmandrels of the tool which is undesirable. The application of too littlezinc chromate leads to certain other problems such as inadequatecorrosion protection wherein undesirable galvanic corrosion 111 maydevelop across the fastener 114 and the threaded nut barrel 178. (SeeFIGS. 1A-1B). The galvanic corrosion 111 comprises the strength of thefastener assembly 110 and causes an unsightly appearance of the overallassembly due to the visibility of the corrosion across the fastenerassembly 110. Other coatings may be formed from a fluoropolymercomposition which is coated onto a stainless-steel fastener. However,aside from insufficient protection from galvanic corrosion when coatinga fastener 114 (as previously noted), the additional step of applying acoating, sealant or plating to the insert can lead to added expense inthe manufacturing process.

Accordingly, there is a need to provide a fastening assembly whichprovides improved resistance to galvanic corrosion in a cost-effectivemanner.

SUMMARY

The present disclosure provides a fastening assembly which may include apanel, a fastener and a primary anode insert wherein the primary anodeinsert is configured to function to preferentially undergo galvaniccorrosion while the fastener (the secondary anode metal/alloy)experiences inhibited corrosion. Moreover, multiple embodiments of thepresent disclosure provide a fastening assembly which maintains itsappearance despite undergoing galvanic corrosion. The panel defines anaperture and the fastener includes a shaft portion disposed within theaperture. The primary anode insert may be disposed adjacent to areaction region of the fastener. The panel may, but not necessarily, beformed from a carbon fiber reinforced thermoplastic material and thefastener may be formed from steel. Moreover, the primary anode insertdefines an insert thickness and a shape between an upper surface and alower surface. In one non-limiting example, the primary anode may be awasher. In another non-limiting example, the primary anode insert may bean elongated member such as, but not limited to a pin. Theaforementioned fastener may, but not necessarily, be a rivet or a flowscrew, nut, stud, and/or bracket.

In the example where the fastener is a rivet, the primary anode insertmay be disposed adjacent to at least one of an interior ceiling surfaceof the rivet, a flange curve of the rivet, and a distal end of therivet. It is understood that the rivet further defines a flange whichmay cover the primary anode insert and secure the primary anode insertagainst the panel. However, it is also understood that the flange mayalternatively only cover a portion of the primary anode insert. Withrespect to the example where the fastener is a flow screw (self-piercingor extruding screw), the flow screw includes a cap which may cover theprimary anode insert and secure the primary anode insert against anupper surface of the panel.

However, it is understood that the fastening assembly may optionallyfurther comprise a retention component which engages with an engagementfeature in the fastener. In this example having the additional retentioncomponent, the fastener may optionally be a mandrel and the retentioncomponent may be a sleeve. The mandrel may define a shaft integral to ahead having an anode insert affixed to the head 63, and the sleeve maydefine a sleeve flange and a cylindrical body. In this embodiment, thefastening assembly may further include a secondary anode insert disposedbetween the sleeve flange and the panel.

In yet another example having the additional retention component, thefastener may optionally be a bolt having a threaded shaft and theretention component may be a nut (or collar) which is threaded (orswaged) onto the bolt's threaded shaft. In the aforementionednon-limiting example, a secondary anode insert may be disposed betweenthe nut and a lower surface of the panel, and the primary anode insertbeing disposed between a cap of the bolt and the upper surface of thepanel.

In yet another embodiment of the present disclosure, the fasteningassembly may include a fastener and a primary anode insert. The fastenerincludes a shaft portion which is configured to be disposed within atleast two aligned component apertures. The primary anode insert may bealso be disposed adjacent to a reaction region of the fastener. Theprimary anode insert may define an insert thickness between an uppersurface and a lower surface. The fastener may, but not necessarily, beone of a rivet or a flow screw. However, it is understood that thefastener assembly may further comprise a retention component wherein thefastener may, but not necessarily be a bolt having a threaded or amandrel. The retention component is configured to engage with anengagement feature in the fastener. Where the fastener is a mandrel, theretention component may be a sleeve. However, where the fastener is abolt, the retention component may be a nut threaded onto the threadedshaft of the bolt. It is understood that secondary anode inserts may beimplemented as part of the fastener assembly when a retention componentis implemented.

The present disclosure and its particular features and advantages willbecome more apparent from the following detailed description consideredwith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present disclosure willbe apparent from the following detailed description, best mode, claims,and accompanying drawings in which:

FIG. 1A is a top view of a plurality of fasteners used to secure acarbon fiber reinforced polymeric panel.

FIG. 1B is a bottom view of the plurality of fasteners in FIG. 1A usedto secure the carbon fiber reinforced polymeric panel.

FIG. 2A is a cross-sectional view of a first embodiment of the presentdisclosure.

FIG. 2B is a top view of the anode inserts used in FIG. 2A.

FIG. 3A is a cross sectional view of a second embodiment of the presentdisclosure prior to installation onto a panel.

FIG. 3B is a cross-sectional view of the second embodiment in FIG. 3Awhen the fastener is fully installed.

FIG. 4 is a cross-sectional view of a third embodiment of the presentdisclosure.

FIG. 5A a cross-sectional view of a fourth embodiment of the presentdisclosure.

FIG. 5B is a cross-sectional view of a fifth embodiment of the presentdisclosure.

FIG. 5C is a cross-sectional view of the fastener assembly using a rivetwherein the anode insert is forged into the distal end of the rivet.

FIG. 6A is a cross-sectional view of a sixth embodiment of the presentdisclosure wherein the anode insert is partially exposed.

FIG. 6B is a top view of the fastening assembly in FIG. 6A.

Like reference numerals refer to like parts throughout the descriptionof several views of the drawings.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferredcompositions, embodiments and methods of the present disclosure, whichconstitute the best modes of practicing the present disclosure presentlyknown to the inventors. The figures are not necessarily to scale.However, it is to be understood that the disclosed embodiments aremerely exemplary of the present disclosure that may be embodied invarious and alternative forms. Therefore, specific details disclosedherein are not to be interpreted as limiting, but merely as arepresentative basis for any aspect of the present disclosure and/or asa representative basis for teaching one skilled in the art to variouslyemploy the present disclosure.

Except in the examples, or where otherwise expressly indicated, allnumerical quantities in this description indicating amounts of materialor conditions of reaction and/or use are to be understood as modified bythe word “about” in describing the broadest scope of the presentdisclosure. Practice within the numerical limits stated is generallypreferred. Also, unless expressly stated to the contrary: percent,“parts of,” and ratio values are by weight; the description of a groupor class of materials as suitable or preferred for a given purpose inconnection with the present disclosure implies that mixtures of any twoor more of the members of the group or class are equally suitable orpreferred; the first definition of an acronym or other abbreviationapplies to all subsequent uses herein of the same abbreviation andapplies to normal grammatical variations of the initially definedabbreviation; and, unless expressly stated to the contrary, measurementof a property is determined by the same technique as previously or laterreferenced for the same property.

It is also to be understood that this present disclosure is not limitedto the specific embodiments and methods described below, as specificcomponents and/or conditions may, of course, vary. Furthermore, theterminology used herein is used only for the purpose of describingparticular embodiments of the present disclosure and is not intended tobe limiting in any way.

It must also be noted that, as used in the specification and theappended claims, the singular form “a,” “an,” and “the” comprise pluralreferents unless the context clearly indicates otherwise. For example,reference to a component in the singular is intended to comprise aplurality of components.

The term “comprising” is synonymous with “including,” “having,”“containing,” or “characterized by.” These terms are inclusive andopen-ended and do not exclude additional, un-recited elements or methodsteps.

The phrase “consisting of” excludes any element, step, or ingredient notspecified in the claim. The phrase “consisting essentially of” limitsthe scope of a claim to the specified materials or steps, plus thosethat do not materially affect the basic and novel characteristic(s) ofthe claimed subject matter.

The terms “comprising”, “consisting of”, and “consisting essentially of”can be alternatively used. Where one of these three terms is used, thepresently disclosed and claimed subject matter can include the use ofeither of the other two terms.

Throughout this application, where publications are referenced, thedisclosures of these publications in their entireties are herebyincorporated by reference into this application to more fully describethe state of the art to which this present disclosure pertains.

The following detailed description is merely exemplary in nature and isnot intended to limit the present disclosure or the application and usesof the present disclosure. Furthermore, there is no intention to bebound by any theory presented in the preceding background or thefollowing detailed description.

Referring now to FIGS. 2A-6B, the present disclosure provides afastening assembly 10 which may include a plurality of panels 12, afastener 14 and a primary anode insert 18. With respect to allembodiments of the present disclosure, the fastener 14 (non-limitingexamples shown in FIGS. 2A-6B) has a higher electrode potential than theprimary anode insert 18. The fastener 14 of the present disclosure maybe provided in a variety of forms, such as but not limited to rivet, aflow screw, a bracket, a stud. As noted, a bracket may also be viewed asa component of a fastening assembling given that a bracket may be usedto couple one member to another member.

Each panel 12 may optionally be formed from material with high potential(e.g., carbon fiber thermoplastic material) 26 which is very resistantto corrosion. In this circumstance, galvanic corrosion at the fasteningassembly 10 may be accelerated given that panels 12 made from carbonfiber thermoplastic material 26 are very resistant to corrosion. Eachpanel 12 defines an aperture 20 and the fastener 14 includes a shaftportion 22 disposed within the aperture 20. The primary anode insert 18may be disposed adjacent to a reaction region 24 of the fastener 14. Thefastener 14 may be formed from metal (e.g., steel, stainless steel,etc.). Moreover, the primary anode insert 18 may define an insertthickness 32 between an upper surface 34 and a lower surface 36. Asshown in FIGS. 2A-5A, the primary anode insert 18 may be completelyembedded (or hidden) under the cap/flange of the fastener (or sleeveflange) so that the cosmetic appearance of the overall fasteningassembly will not be detracted by the sacrificial corroding primaryanode insert. The aforementioned fastener 14 may, but not necessarily bea rivet 42 or a flow screw 44. In one non-limiting example, the primaryanode insert 18 may be a washer 38. In another non-limiting example, theprimary anode insert 18 may be an elongated member 40 such as a pin 19(see FIG. 3B) which may be press-fitted into the fastener 14 (shown as amandrel 64 in FIG. 3B). Regardless of the configuration of the anodeinsert, the amount (weight) of the anode insert would depend on thecontact area between the metal fastener and cathode (e.g., carbon fibercomposite). The anode insert 18 should have sufficient material suchthat it would last for the life time of the fastener (e.g., 15 years forautomotive application).

However, with reference to FIGS. 2A-3B, it is understood that thefastening assembly 10 may optionally further comprise a retentioncomponent 60 which engages with an engagement feature 62 in the fastener14. In the non-limiting examples shown in FIGS. 3A-3B having theadditional retention component 60, the fastener 14 may optionally be amandrel 64 and the retention component 60 may be a sleeve 66 (see FIGS.3A-3B) wherein the mandrel 64 deforms the sleeve 66 to form thefastening assembly 10. The mandrel 64 may define a shaft 68 integral toa head 63 having an anode insert affixed to the head 63, and the sleeve66 may define a sleeve flange 70 and a cylindrical body 72. The primaryanode insert 18 may be affixed to the head 63 in various ways. In oneexample, the primary anode insert 18 may be a pin 19 which is insertedinto an aperture 21 defined in the head 63. (see FIG. 3B). In anothernon-limiting option, the primary anode insert 18 may be press-fittedinto a groove/cavity/aperture 21 defined in the head 63. In thisembodiment, the fastening assembly 10 may further include a secondaryanode insert 78 disposed between the sleeve flange 70 and each panel asshown in FIGS. 3A-3B.

With reference back to FIGS. 2A-2B, another example having theadditional retention component 60 is shown wherein the fastener 14 isprovided in the form of a bolt 74. The bolt 74 includes a threaded shaft76 and the retention component 60 may be a nut (or collar) 79 which isswaged onto the bolt's threaded shaft 76. In the aforementionednon-limiting example, a secondary anode insert 78 may be integrated intothe retention component 60 (nut 79 in FIG. 2A) such that the secondaryanode insert 78 is adjacent to a lower surface 80 of the plurality ofpanels 12, and the primary anode insert 18 is integrated into the cap 82of the bolt 74 such that the primary anode insert 18 is adjacent to theupper surface 58 of the plurality of panels 12. It is understood thatthe primary anode insert 18 in FIGS. 2A-2B is configured topreferentially undergo galvanic corrosion while the fastener 14 in theform of the bolt 74 and nut 79 experiences inhibited corrosion.Accordingly, the strength of the fastening assembly 10 is notcompromised despite the galvanic corrosion which is concentrated at theprimary anode insert 18 and secondary anode insert 78 because thecorroded anode insert(s) 18, 78 are not located in a high stress region(at the stress raiser).

With reference to FIGS. 5A-6B, the fastener 14 may be provided in theform of a rivet 42 wherein the primary anode insert 18 may be disposedadjacent to at least one of an interior ceiling 46 surface of the rivet42 (see FIG. 5A), a flange curve 48 of the rivet 42 (see FIG. 5A), and adistal end 50 of the rivet 42 (see FIGS. 5B-5C). As shown in FIG. 5A, itis understood that the rivet 42 may further define a flange 52 which maycover the primary anode insert 18 and secure the primary anode insert 18against each panel. However, it is also understood that the flange 52may alternatively only cover a portion 54 of the primary anode insert 18as shown in FIGS. 6A-6B. It is understood that the primary anode insert18 in FIGS. 5A-6B is configured to preferentially undergo galvaniccorrosion while the fastener 14 in the form of the rivet 42 experiencesinhibited corrosion. Accordingly, the strength of the fastening assembly10 is not compromised despite the galvanic corrosion which isconcentrated at the primary anode insert 18 because the corroded anodeinsert 18 is not located at the stress raiser. Moreover, given that theanode insert 18 is hidden under the flange 52, the cosmetic appearanceof the fastening assembly is not compromised as the anode insert 18undergoes (sacrificial) galvanic corrosion.

In yet another embodiment of the present disclosure, the fasteningassembly 10 may simply include a fastener 14 and a primary anode insert18 as shown in FIGS. 2A-6B. As shown in the aforementioned figures, thefastener 14 includes a shaft portion 22 which is configured to bedisposed within at least two aligned component apertures 84. As shown,each primary anode insert 18 may be also be disposed adjacent to areaction region 24 of the fastener 14. The primary anode insert 18 maydefine an insert thickness 32 between an upper surface 34 and a lowersurface 36. With reference to FIGS. 4-6B, the fastener 14 may, but notnecessarily, be one of a rivet 42 (see FIGS. 5A-6B) or a flow screw 44(see FIG. 4). However, as shown in FIGS. 2A-3B, it is understood thatthe fastener 14 assembly may further comprise a retention component 60wherein the fastener 14 may, but not necessarily be a bolt 74 having athreaded shaft 76 or a mandrel 64. As shown in FIGS. 2A-3B, theretention component 60 is configured to engage with an engagementfeature 62 in the fastener 14. With reference to FIGS. 3A-3B, thefastener 14 is provided in the form of a mandrel 64, and the retentioncomponent 60 is provided in the form of a sleeve 66. Sleeve 66 isconfigured to deform (see FIG. 3B) when mandrel 64 engages with thesleeve 66. However, as shown in FIGS. 2A-2B, where the fastener 14 isprovided in the form of a bolt 74, the retention component 60 may beprovided in the form of a nut 79 which is swaged onto the threaded shaft76 of the bolt 74. It is understood that secondary anode inserts 78 maybe implemented as part of the fastener 14 assembly when a retentioncomponent 60 is used as part of the assembly as shown in FIGS. 2A-3B.Accordingly, the primary anode insert(s) 18 in FIGS. 5A-6B is configuredto preferentially undergo galvanic corrosion while the fastener 14 (thesecondary anode metal/alloy) in the form of the rivet 42 experiencesinhibited corrosion. Accordingly, the strength of the fastening assembly10 is not compromised despite the galvanic corrosion which isconcentrated at the primary anode insert 18.

Referring now to FIG. 4, the fastener 14 may be provided in the form ofa flow screw 44 wherein the flow screw 44 includes a cap 56 which maycompletely cover the primary anode insert 18 and secure the primaryanode insert 18 against an upper surface 58 of the plurality of panels12. Similarly, the primary anode insert 18 in FIG. 4 is configured topreferentially undergo galvanic corrosion while the fastener 14 in theform of the flow screw 44 experiences inhibited corrosion. Accordingly,the strength of the fastening assembly 10 is not compromised despite thegalvanic corrosion which is concentrated at the primary anode insert 18.Moreover, the cap 56 of the flow screw 44 obscures the view of primaryanode insert 18 as it undergoes galvanic corrosion.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thedisclosure in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the exemplary embodiment or exemplary embodiments. Itshould be understood that various changes can be made in the functionand arrangement of elements without departing from the scope of thedisclosure as set forth in the appended claims and the legal equivalentsthereof.

What is claimed is:
 1. A fastening assembly comprising: a panel definingan aperture; a fastener having a shaft portion disposed within theaperture; and a primary anode insert disposed adjacent to a reactionregion of the fastener.
 2. The fastening assembly as defined in claim 1wherein the panel is formed from a carbon fiber reinforced thermoplasticmaterial and the fastener is formed from steel.
 3. The fasteningassembly as defined in claim 1 wherein the primary anode insert definesan insert thickness between an upper surface and a lower surface.
 4. Thefastening assembly as defined in claim 3 further comprising a retentioncomponent which is configured to engage with an engagement feature inthe fastener.
 5. The fastening assembly as defined in claim 3 whereinthe fastener is one of a rivet, a flow screw, a bracket, or a stud. 6.The fastening assembly as defined in claim 5 wherein the fastener has ahigher electrode potential than the primary anode insert.
 7. Thefastening assembly as defined in claim 4 wherein the fastener is amandrel and the retention component is a sleeve.
 8. The fasteningassembly as defined in claim 4 wherein the fastener is a bolt having athreaded shaft and the retention component is a nut threaded onto thethreaded shaft.
 9. The fastening assembly as defined in claim 5 whereinthe primary anode insert is disposed adjacent to at least one of aninterior ceiling surface of the rivet, a flange curve of the rivet, anda distal end of the rivet.
 10. The fastening assembly as defined inclaim 9 wherein a flange of the rivet covers the primary anode insertand secures the primary anode insert against the panel.
 11. Thefastening assembly as defined in claim 9 wherein a flange of the rivetcovers a portion of the primary anode insert.
 12. The fastening assemblyas defined in claim 6 wherein a cap of the flow screw covers the primaryanode insert and secures the primary anode insert against the panel. 13.The fastening assembly as defined in claim 7 wherein the mandrel definesa shaft integral to a head having an anode insert affixed to the head,and the sleeve defines a sleeve flange and a cylindrical body.
 14. Thefastening assembly as defined in claim 13 further comprising a secondaryanode insert disposed between the sleeve flange and the panel.
 15. Thefastening assembly as defined in claim 8 further comprising a secondaryanode insert being disposed between the nut and a lower surface of thepanel, and the primary anode insert being disposed between a cap of thebolt and the upper surface of the panel.
 16. A fastening assemblycomprising: a fastener having a shaft portion configured to be disposedwithin at least two aligned component apertures; and a primary anodeinsert disposed adjacent to a reaction region of the fastener.
 17. Thefastening assembly as defined in claim 16 wherein the primary anodeinsert defines an insert thickness between an upper surface and a lowersurface.
 18. The fastening assembly as defined in claim 17 furthercomprising a retention component which is configured to engage with anengagement feature in the fastener.
 19. The fastening assembly asdefined in claim 17 wherein the fastener is one of a rivet or a flowscrew.
 20. The fastening assembly as defined in claim 18 wherein thefastener is a mandrel and the retention component is a sleeve.
 21. Thefastening assembly as defined in claim 18 wherein the fastener is a bolthaving a threaded shaft and the retention component is a nut threadedonto the threaded shaft.